Non-core coronoid

A coronoid which is not a core coronoid, is sometimes called a non-core coronoid. 

If a coronoid has a furing edge it must necessarily be a core coronoid. Notice also that all fusing edges disappear from a coronoid as soon as it is circumscribed (if possible). Finally it is noted that c(Cq) very well may be a non-core coronoid even if Cq is a core coronoid. An example is shown below. 

In Fig. 4.2 (cf. also Fig. 2) all the systems in the top and bottom rows are core benzenoids or core simple coronoids. The two first systems in the middle row (viz. C24H12 and C32H14) are not core benzenoids, while the last system therein (viz. C66H22) is a non-core single coronoid. There exist core coronoids of different natures, as is explained below. 

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